Belt conveyor drives utilizing a primary and a secondary drive drum or pulley to transmit horsepower into a stretchable fabric construction belt have operated for many years. The dual drive pulley arrangement or tandem drive is powered by electric motors which are coupled through reducers to each pulley shaft. The ability to effectively transmit the installed horsepower requires load sharing between the primary and secondary drives.
To achieve proper load sharing without direct coupling of the primary and secondary pulleys, such as with tie gears, has presented a problem and has in some instances resulted in overdesigning of the system to compensate for unequal power sharing. Tandem conveyor drives which have been manufactured without tie gears begin to overload the secondary drive modules once the conveyor load exceeds approximately 65% of the installed horsepower. Attempts have been made to accomplish load sharing by using different drum diameters and electric motor speed control methods but with limited success. In conventional systems, direct coupling the pulleys with timing gears appears to be the only positive method of achieving electric load sharing.
It is accordingly an object of the present invention to provide a non-mechanical method of load sharing so that both the primary and secondary drive motors load up evenly between the drive modules.